1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a LCD device having a design of a bonding pad between a LCD panel and a flexible printed circuit.
2. Description of the Prior Art
Owing to their low-profile, thin, and lightweight features, LCD devices have replaced cathode ray tubes (CRTs) in many applications and becomes the mainstream display devices in recent years. LCD panels are widely used in electronic devices such as mobile phones, personal digital assistants (PDAs), digital cameras, computer screens, notebook screens, etc.
A conventional liquid crystal display (LCD) device comprises a LCD panel and external driving chips. The external driving chips transmit scan or data signals to pixels of the LCD panel to display images via metallic wires on the LCD panel.
The external driving chips and the LCD panel are coupled through a flexible printed circuit (FPC) on which metallic wires are set up. One end of each metallic wire on the FPC is coupled to output of the external driving chips, and the other end of each metallic wire on the FPC is coupled to each metallic wire of the LCD panel. Due to the arrangement, the driving chips can output signals to the LCD panel successfully.
In addition, the metallic wires of the FPC are bonded to the metallic wires of the LCD panel. In the prior art, there is a convex FPC bonding pad at the end of each metallic wire on the FPC, and there is also a convex panel bonding pad at the end of each metallic wire on the LCD panel. In the process of bonding, anisotropic conductive film (ACF) is coated on the surface of the LCD panel. Then the FPC bonding pads target at and stick to the panel bonding pads. Conductive particles in the ACF are crushed by pressing and heating, so that the FPC bonding pads couples the panel bonding pads.
Please refer to FIG. 1. FIG. 1 is a local diagram of a LCD device 100 in the prior art. To facilitate the description, FIG. 1 only shows bonding areas of the FPC and the LCD panel. The panel bonding pad 110 is designed as one section. Every bonding pad 110 has the same area. All pitches between any two neighboring bonding pads 110 are identical. The FPC bonding pad 120 is also designed correspondingly to the panel bonding pad 110 for bonding.
Owing to panel resolution being getting higher, more data lines are needed to be disposed on the LCD panel. Hence it is necessary to set up more bonding pads. The measure of bonding area, however, is actually limited. Therefore, the solution is to reduce the areas of the bonding pad/FPC bonding pad and to reduce a pitch between two neighboring panel bonding pads and between two neighboring FPC bonding pad. But it is ineffective to mass production because machine precision leads to misalignment of the panel bonding pad and FPC bonding pad of probably the to cause abnormal signal transmission.